In Vivo Potassium-39 MRI at 9.4 Tesla Using a Room-Temperature Surface Resonator: Does Cryogenic Cooling Help?

Ibrahim A. Elabyad¹, Friedrich Wetterling¹, Nagesh Shanbhag², Lothar Schilling², Lothar R. Schad¹

In the current feasibility study, a single-tuned 39K surface resonator was developed and tested for the measurement of 39K signal in the normal live rat brain. Compared with the previous published results, the herein used CSI technique in conjunction with improved resonator sensitivity achieved approximately 5 times higher SNR in half the acquisition time. Additionally, the S/N improvement by cryogenic cooling the resonator was estimated from simulated copper RF-coil at room-temperature (RT) of 293 K and cryogenic temperature (CT) of 90 K. For both coils, full-wave Electro-Magnetic (EM)-simulations were computed for a single loop resonator with 35-mm diameter and 1.5-mm wire thickness for unloaded and loaded conditions. Results show that, 2.3-fold sensitivity improvement is expected when the coil is cooled down to 90 K, which could further improve the available signal in future 39K-MR imaging studies of the rat brain at 9.4T. In conclusion, 39K-MRI of the rat brain is possible at 9.4T using a CSI sequence and a single-tuned surface resonator and 39K resonator sensitivity can be further improved by cryogenic cooling.